Weft straightener



Sept. 23, 1947. V055 EIAL 4 2,427,753

WEF'I STRAIGHTENBR I Filed April 5. 1946 3 Sheets-Sheet 3 mvzu'rons Ron-0r W. Vac: ANQ BY Campus. PLuMMtR ATTORNEY Patented Sept. 23, 394? WEFT STRAIGHTENER Robert'W. Vose, West 8 Springfield, Chicopee Manufacturi ration of Massachuse Plummer.

pringiield and Charles 1!.

Mass, aaaignors to tn: Corporation, a corpo.

Application April 3, 1946, Serial No. 659,288

' 17 Claims.

This invention relates to devices for straightening the weft of woven fabrics. When fabric is woven the weft threads are straight and perpendicular to the warp, but in subsequent treatment or finishing the weft sometimes becomes crooked. This is particularly apt to occur in the bleaching and finishing oi lightweight, coarse weave or low-count cotton fabric, such as gauze or marquisette, but may occur in any fabric. The crooked weft may take various forms. It may be skewed, that is the weft threads may be either rectilinear or wavy, but they slant across the warp; or it-may be bowed, in which case the weft threads are curved, and may or may not be skewed; or the weft may take the form of a Z, in which case the opposite ends of a single weft thread may or may not be perpendicular to the warp, but the ends are not in opposite positions on the warp, one edge of the warp being advanced'with respect to the other.

It is desirable to have the weft threads straight (that is both rectilinear and perpendicular to the warp) when the fabric is finished and to this end various devices have been proposed for detecting crooked weft and straightening it before the treating process is completed. Such apparatus as has come to our attention has the disadvantage that it is complicated, expensive toman- I ufacture, difficult to maintain and unreliable in.

its operation. Furthermoreit is diilicult to embody in one apparatus the devices which are necessary to straighten the various forms of crooked weft enumerated above.

The objects of our invention areto provide an improved, simple apparatus for straightening weft which is economical to manufacture and easy to maintain, and which is reliable in operation. The invention is especially advantageous when applied to light-weight, low-count cotton fabrics, but is equally applicable to any woven fabric, even including insect screen cloth woven of plastic or metal mcnofllaments.

In the accompanying drawings,

Fig. 1 is a magnified diagrammaticplan of a portion of textile fabric illuminated according to our invention;

Fig, 2 is a section perpendicular to Fig. 1;

Fig. 3 is' a view corresponding to Fig. 1 of a a portion of fabric having skewed weft;

Fig. 4 is a diagrammatic plan of fabric having a Z weft'distortion;

. Fig. 5 is a diagrammatic perspective view of one form of apparatus embodying our invention;

Fig. 6 is a diagram of the control circuits for the apparatus shown in Fig. 5;

Fig. 'i is a diagrammatic plan of a different arrangement of apparatus especially adapted] to a removing bow from the weft of fabric; and

Fig. 8 is a diagram of the control circuits for the apparatus shown in Fig. 7.

Referring to Figs. 1 and 2, ii) represents the warp'threads of any woven fabric whether woven of spun yarns customary in cotton or woolen cloth, or of monofilaments, for example metal or plastic screen cloth, and H represents the weft or filling threads. In accordance with our inventlon we illuminate the fabric by parallel rays of light in a flat beam which is nearly parallel to the cloth. These rays are represented by the arrows it. They lie in planes which are perperdicular to the fabric and parallel to the warp threads, and the rays incline downward in these .80 planes to strike the cloth as shown in Fig. 2. If

, the weft threads are perpendicular to the warp threads and hence perpendicular to the rays of light, as indicated in Fig. i, any light reflected by the weft threads will'be directed equally toward 25 both sides 01' the fabric as indicated by the arrows of equal length it and il. Weft threads of smooth monofilaments may reflect negligible amounts of light across the fabric, but yarns spun from textile fibers will act as diffusing refiectors and reflect substantial and equal amounts of light toward the edges of the fabric. However, if the weft threads slant with respect to the warp threads, as indicated in Fig. 3, they will reflect more light toward one edge of the fabric 85 than toward the other side. This is represented by the longer arrows II and the shorter arrows Our invention makes use of this condition to control the position and straightness of the weft threads in fabric as it is being continuously processed.

In customary finishing processes a continuous I strip of fabric 20 passes through a conventional pair of mangle rolls 22 at the left of Fig. 5 and a conventional tenter 24 at the right of Fig. 5. the tenter drawing the fabric against the resistance of the manglerolls and maintaining tension in the warp of the fabric. The strip passes over guide rolls 2! and over a weft'straightener in- 6 eluding a conventional canting roll 28 mounted in slidable guidesfl and 28. the canting roll being suitably tipped and moved from time to time to preserve the weft perpendicular to the warp. The tipping is accomplished by rotating 9. thread- 55 ed shaft 28 which, through suitable links, simultaneously raises the bearing 21 and lowers the 'bearing II or vice versa. Heretofore the canting roll has been controlled either by the complicated and unsatisfactory mechanical control apparatus referred to, or by hand by an operator depending on visual inspection of the fabric. The visual in: spection is unsatisfactory and unreliable at the high speeds at which the fabric usually travels and hand control is not sufficiently constant or reliable to maintain desirably straight weft.

Our invention provides an improved control or 'actuator for weft straighteners which maintains sources of parallel light arranged to direct a flat sheet of small parallel beams against the illuminated none. The sources of light are represented by focused spot lights 8!. The parallel beams strike the zone between the rollers II at a relatively low angle of incidence indicated by the angle ii in Pig. 2.

On either side er the illuminated zone. and slightly above its plane, is placed a light collecting lens II or 3|. Each of these catches rays of light reflected by the weft threads in planes perpendicular to the warp, such rays being at an angle to the warp which is of the order of the angle II in Fig. 2. y

The angle of incidence Il may vary widely, but there is a best angle for each type of cloth, depending on the. coarseness of weave. that is. the spacing between weft threads. .In general. the sensitivity of the control is increased with decreasing angle of incidence. but the best angle of incidence is not low enough to cause one weft thread to cast a shadow on its adjacent thread. As a specific example we have found an angle of about 10 to besatisfactory with cotton gauze having from 12 to weft threads per inch.

Preferably the held of the lens covers the entire width of the cloth. so that the lens gathers light or integrates the reflection from the entire width of the strip. The light gathered by each lens is focused upon any suitable photoelectric cell ll or-fl respectively. which is of a character and no current delivered to the motor starter,

I so that the motor remains stationary.

.diflusely reflected by warp threads.

In the case of ordinary cloth fabric, the total light received by the cells will be made up of light reflected by the weft threads plus some light However, since the warp is symmetrical with respect to the lenses, this warp reflection will be equal in both cells, and can be neglected. Thus if one cell receives more light than the other, this indicates asymmetrical distribution of the weft threads as indicated in Fig. 3 or Fig. 4. This unbalances the bridge circuits to turn the motor 50 in the direction which will cant the roll 28 to correct the misalignment of the warp threads. For example, if the upper or lefthand end of the weft is running ahead of the lower or righthand end, as

seen in Fig. 5, producing a skewed weft shown in Fig. 3, the lefthand end of the roll 28 is elevated and the righthand endvlowered. This causes the lefthand edge to travel farther than the righthand edge, thus slowing it down with respect to the righthand edge. It'also increases the tension of the warp progressively across the width of the fabric. This gradually straightens the weft, balancing the reflected light and hence balancing the bridge circuits to stop the motor.

, 'One advantage of our invention is that the lenses 36 and II can be arranged automatically to add the effect of the light reflected by the weft threads over an area of the fabric extending across the entire width of the fabric and for substantial length in the direction of the warp. This facilitate the straightening of 2, indicated in Fig. 4, for in such case the end-portions of the weft threads which lie straight reflect equal amounts of light to the two lenses, but the center portion reflects different amounts of light and unbalances the circuits as described above. Thus. whenever the circuits are balanced, the fabric will be maintained with the weft threads symmetrical and having their ends opposite each other. However, this may leave a symmetrical bow in the weft which reflects equal amounts of light to the twolenses. If the bow is slight, it may be automatically removed by the tension of the tenterr lines "I. It is illuminated in a zone similar to to control an electric circuit in response to the amount or intensity of light focused upon it.

Any suitable weft straightening apparatus is.

used to straighten or position the weft in response to differential reflection of light by the weft threads as measured by the two photoelectric cells. for example as indicated in Fig. 6., The cells 'II and l! are connected to any suitable known bridge and amplifier ll supplied with power from source II and delivering current to any appropriate reversing motor starter which through connection is controls a conventional reversing motor ll connected through suitable gearing to the threaded shaft is which operates the links for canting the roll I. The arrangement is such that when the light received by the two cells ll 4! is equahthe bridee circuits are balanced that previously described by a second elongated .light source indicated by 02; Two lens and photoelectric, cell units A and D, similar to the units previously described are placed on opposite sides of the strip. The unit A is focused to gather-the light reflected from alone a extending from the adjacent edge of the fabric substantially to the center of the strip and a unit I) focused to gather the light reflected from a'sone d extending from its adjacent edge of the fabric substantially to the center, both zones reflecting light at a low angle corresponding to the angle ll of Fig. 2. The units are so placed that A does not receive light from zone d, and D does not receive light from zone a. A second pair of similar units 8 and -C is placed in advance of the pair AD and on opposite sides of the strip. The unit B is focused to sathenlight from afzone b on the opposite side of the strip and extending from'the edge" substantially to the center, and the unit 0 gathers light from an opposite zone 0 extending from the edge substantially to the center. The unit B does not gather light from acne ment across the fabric or displaced longitudinally of the warp.

It will be observed that when the weft threads are bowed, as indicated in Fig. 7. the portion of the threads in zone a are so inclined that their light sides reflect a relatively large amount of light into unit A, but the threads in zone b reflect little, if any, light into unit B because unit 8 is focused on the dark sides of the threads.- Zone b does not reflect any light into unit C because unit C is not focused on this zone. Likewise, the light sides of the threads in zone d reflect a relatively large amount of light into unit D and the dark sides of the threads in zone reflect little or no light into unit C. Consequently as long as the threads are bowed, the light integrated by units A and D will exceed the light integrated by units B and C. But if the threads are straight, light integrated by units A and D will equal the light integrated by units B and C, because substantially the same amount of light will be reflected from each zone to its associated unit.

Referring to Fig. 8, the units A and D are'connected to a bridge and amplifier so that their output adds. Likewise the units B and C are connected to the bridge and amplifier so that their output adds. Whenever the weft threads are bowed, zone a reflects more light to unit A than zone b reflects to unit B, and zone d reflects more light to unit D than zone 0 reflects to'unit C, and consequently a plus (1 will be greater than I) plus 0. This will unbalance the bridge which is connected to control any suitable bow-straightener, such as the motor 64 which, through suitable gearing, rotates .a, bowed shaft 66 mounted light reflected by the zone d. Consequently a plus 11 equals 0 plus d, and the bridge becomes balanced to stop the control motor with the rod out of contact with the fabric strip.

We claim as our invention:

1. In a weft straightener the combination of means for moving in the direction of its warp a strip of fabric having warp and weft threads, means for illuminating the fabric by rays of light in planes transverse to the fabric and parallel to the warp threads, and means for controlling the position of the weft threads with respect to the warp threads in response to the differential reflection of light from said illuminating means toward opposite edges of the fabric by the weft threads.

2. In a weft straightener for fabric having warp and weft threads, the combination of means for illuminating the fabric by rays of light in planes transverse to the fabric and parallel to the warp threads, and means for positioning the weft threads perpendicular to the warp threads in response to the simultaneous reflection of different amounts of light by the weft threads from said illiuninating means toward opposite edges of the fabric.

3. In a weft straightener for a strip of fabric having warp and weft threads, the combination of means for illuminating the fabric by, rays of light in planes transverseto the fabric and parallel to the warp threads, means on opposite sides of the strip for detecting light from said illuminating means reflected by the weft threads toward opposite edges of the strip, and means responsive to differences in the amount of light detected by said two means for positioning the weft threads perpendicular to the warp.

4. In a weft straightener for fabric having warp and weft threads. the combination of means for illuminating the-fabric by rays of light in planes transverse to the fabric and parallel to the warp threads, means for measuring light from said illuminating means reflected by the weft threads toward opposite edges of the fabric,

and means responsive to differences in the amount of light reflected toward opposite edges for advancing one edge of the fabric with re spect to the other edge of the fabric. 5. In a weft straightener a combination of means for moving in the direction of its warp a strip of fabric having warp and weft threads, means for exerting tension on the fabric warp, means for illuminating th fabric by rays of light in planes transverse to the fabric and parallel to the warp threads, and means for con- 1 6. In a weft straightener for fabric having warp and weft threads, the combination of means for exerting tension in the direction of its warp, means for illuminating the strip by rays of light in planes transverse to the fabric and parallel to the warp threads, and means for changing the tension of the warp threads progressively across the fabric in response to the difference in the amounts'of light from said illuminating means reflected by the weft threads toward opposite edges of the fabric.

7. In a weft straightener a combination of means for moving in the direction of its warp a strip of fabric having warp and'weft threads, means for illuminating the fabric by rays of light in planes transverse to the fabric and parallel to the warp threads, means changing the relative speed of the edges of the fabric in response to the difference in the amounts of light from said illuminating means reflected by the weft threads toward opposite edges of the fabric.

8. In a weft straightener a combination of means for moving in the direction of its warp a strip of fabric having warp and weft threads,

"means for illuminating the strip by rays of light in planes transverse to the fabric and parallel to the warp threads, 8. canting roll, and means for tipping the canting roll in response to the difference in the amounts of light from said illuminating means reflected by the weft threads to-- ward opposite edges of the fabric.

9. In' a weft straightener for fabric having to the difference in the amount of reflected light reflected toward one side of the fabric and the amount of lightreflected toward the other side of the fabric for controlling the position of the weft threads with respect to the warp threads. 10. In a device for straightening the bow in the weft of fabric having warp and weft threads, the

combination of means for illuminating the fabric by rays of light in planes transverse to the fabric and parallel to the warp threads, means for measuring light from said illuminating means reflected toward the edges of the fabric by the convex sides of bowed weft threads, means for measuring light from said illuminating means reflected toward the edges of the fabric by the concave sides of the bowed weft threads, and means responsive to differences in the amount of light measured by said two means for straightening" the bow.

11. In a device for straightening the bow in the parallel to the warp threads, means for measurlight from said illuminating means reflected by the weftthreads toward one edge of the fabric at low angles of reflection, said means being adapted ing the weft.

15. In a device for straightening the bow in the weft of a fabric having warp strands and weft strands, means for illuminating the fabric by rays of light in planes transverse to the fabric and parallel to the warp strands, whereby the weft strands will reflect light perpendicular to the warp strands, means formeasuring the light reflected from a zone adjacent the flrst edge toward said first edge of the fabric, means for measuring the light reflected from a second zone adjacent the second edge toward said second edge of -the fabric, means for measuring the light reflected from a third zone adjacent the first edge toward the second edge, means for measuring the light reflected from a fourth zone ading light from said illuminating means reflected.

the warp threads, a pair of means spaced along the warp for measuring light from said illuminating means reflected by the weft threads in planes perpendicular to the warp threads, and means responsive to differences in the amount of light measured by said two means for controlling the position of the weft threads with relation to the warp. v a

v 13. In a weft straightener for fabric having warp and weft threads, the combination of means for illuminating the fabric by rays of light in planes transverse to the fabric and parallel to the warp threads, a pair of means spaced along the warp for detecting light from said illuminating means reflected by the weft threads toward the edges of the fabric, each of said means being adapted to measure and, add the effects of the light reflected by increments of length of the weft threads, and means responsive to differences in the amount of light measured by said two means for controlling the position of the weft threads with relation to the warp.

14. In a weft straightener for fabric having warp and weft threads, the combination of means for illuminating an area of the fabric of appreciable length in the direction of the warp by rays of light in planes transverse to the fabric and parallel to the warp threads and at a low angle -of incidence to the fabric, means for detecting- Jacent the second edge toward the flrst edge, and means for straightening the bow in response to the difference between the sum of reflected light measured from the first and second zones and the sum of reflected light measured from the third and fourth zones.

16. In a weft straightener for fabric havins warp and weft strands, the combination of means for illuminating the fabric by rays of light in planes transverse to the fabric and parallel to the warp strands. a first measuring means for measuring the light from said illuminatingmeans reflected by the weft strands toward one edge of the fabric, a second measuring means spaced along the warp from the flrst measuring means, said second measuring means being adapted to measure the light from illuminating means reflected by the weft threads toward the opposite edge of the fabric, and means for controlling the position of the weft strands with relation to the warp strands in response to the difference in the light measured by said two measuring means.

17. Means for controlling the position of weft threads with respect to warp threads of a fabric comprising in combination means for illuminating a fabric by rays of light in planes transverse to the fabric and parallel'to the warp threads,

REFERENCES CITED The following references are of record in the flle of this patent:

UNITED STATES PATENTS Name Date Number La Pierre Jan. 25, 1938 

